What was found
IN FLIGHT MAIN TANK NR 1 WAS 600 LBS LOW WHILE USING CENTER TANK FUEL. ON LANDING MAIN TANK NR 1 300 LBS LOW. GROUNDED - YES. ON DEFERRAL. PERFORMED A TANK AND COMP UNITS TEST ON THE NR 1 TANK PER AMM 28-41-21-710-801. FOUND PROBES F15, F4, F5, F6, F7, AND F9 OUT OF LIMITS. REMOVED AND REPLACED F15L COMPENSATOR AND F4L, F5L, F6L, F7L, F8L, AND F9L TANK UNITS ON NR 1 MAIN TANK PER AMM 28-41-21/401. TANK AND COMPENSATOR UNITS TEST GOOD PER AMM 28-41-21-710-801. GROUND VERIFICATION GOOD.